Experimental Design

Lexi is researching crime rates. She is trying to make a conclusion about whether the crime rate changes with the population in each county in her state. What is the outcome variable (dependent variable) of her investigation?

• the state

• the county

• the crime rate

• the population

Which of the following procedures demonstrates repetition?

• Marco places a toy car at the top of a ramp. He releases the car and measures how long it takes for the car to reach the bottom of the ramp. Then, he returns the car to the top of the ramp, releases the car again, and makes an additional measurement.

• Cynthia monitors the growth rate of her pet turtle. She measures the length and weight of her turtle every Sunday over the course of six months.

• Kasey performs a scientific investigation on the effects of using soda instead of water to hydrate plants. Caleb uses Kasey's procedure and performs the same experiment during the following month.

• Jeremiah measures the mass of five different strips of metal. He places the strips in five different test tubes filled with hydrochloric acid. He observes if heat and bubbles are produced after the metal strips and acid are combined.

Your teacher has asked you to perform an experiment to see if the shape of objects, alone, affects the motion of objects. Which of the following would be the best experiment to perform?

• Apply the same amount of force to a ball, cylinder, cube, and pyramid, each of a different mass.

• Apply the same amount of force to a ball, cylinder, cube, and pyramid, each of the same mass.

• Apply different amounts of force to the same ball.

• Apply the same amount of force to balls of different masses.

A group of scientists follows a set of steps designed to detect metals found in different sources of drinking water. What is the correct order of these steps so that they correctly describe the investigation as the scientists should have performed it.

I. Collect the water samples.

II. Predict whether of not water sources near a manufacturing plant are contaminated.

III. Conclude which, if any, of the water samples have unsafe levels of metal.

IV. Measure the amounts of metals in each sample and record the amounts in a table.

• I, II, III, IV

• II, I, IV, III

• II, I, III, IV

• II, IV, I, III

Tags

NGSS.MS-PS1-2

How do the test variables (independent variables) and outcome variables (dependent variables) in an experiment compare?

• The test variables (independent variables) and outcome variables (dependent variables) are the same things.

• The outcome variable (dependent variable) controls the test variable (independent variable).

• The test variable (independent variable) controls the outcome variable (dependent variable).

• The test variable (independent variable) and outcome variable (dependent variable) have no effect on each other.

In a controlled scientific experiment,

• only one variable can be kept constant.

• no variables are kept constant.

• all variables are kept constant.

• one or more variables are kept constant.

Tags

NGSS.MS-PS3-4

When more than one variable in an experiment is changed at a time, the scientist:

• needs to conduct more trials in order to get conclusive results.

• made a systematic error that needs to be corrected.

• cannot tell which change produced the results.

• cannot accurately measure both variables at the same time.

Sarah wants to know if mice prefer peanut butter over cheese. In what order should she do the following steps?

I. Place the bowl of peanut butter and a block of cheese next to each other in a mouse cage.

II. Predict which food the mice will prefer.

III. Write a report on her findings.

IV. One at a time, place ten mice in the cage and observe which food they eat.

• II, IV, I, III

• I, IV, III, I

• II, I, IV, III

• IV, I II, III

Tags

NGSS.MS-LS2-1

You have a hypothesis that people ages 4 to 35, teenagers will like a new drink called SugarHi better than any other age-group. You want to survey 40 people for their opinions about the drink, but you are unsure how many people to survey from each age group. Which of the answer choices below represents the most fair way to collect the data?

• 10, 10, 10, 10

• 10, 15, 5, 10

• 10, 5, 15, 10

• 5, 30, 2, 3

Shelly wants to know if hummingbirds prefer honey, sugar, or corn syrup. She creates three solutions of equal sweetness. One solution is made of honey and water, the second is sugar water, and the third is corn syrup and water. She places three hummingbird feeders side-by-side outside a window. To make sure she could tell them apart, she puts each solution in a different-colored feeder: one is red, one is yellow, and one is blue. Shelly spent a day collecting data by sitting in the chair and recording her observations about how many hummingbirds came to each feeder, how long they stayed at each, and, when possible, if they returned to a feeder after tasting another. Shelly's experiment will not give conclusive results. What is the most important reason why it will not?

• A. She did not do multiple trials.

• B. "Sweetness" cannot be measured.

• C. The feeders are different colors.

• D. A hummingbird's preference is not observable.

Tags

NGSS.MS-LS2-1